The use of nerve stimulation for treating and controlling a variety of medical, psychiatric, and neurological disorders has seen significant growth over the last several decades. In particular, stimulation of the vagus nerve (the tenth cranial nerve) has been the subject of considerable research. The vagus nerve is composed of somatic and visceral afferents (inward conducting nerve fibers, which convey impulses toward the brain) and efferents (outward conducting nerve fibers, which convey impulses to an effector to regulate activity such as muscle contraction or glandular secretion). The vagus nerve is responsible for controlling and/or receiving feedback from various glands, the pharynx, larynx, heart, lungs, liver, stomach, intestine, and ureters. Because of its large number of functions with respect to a range of body systems, the vagus nerve is preferred in many applications for purposes of modulating the functions of designated organs or portions of the central nervous system (CNS).
U.S. Pat. No. 5,540,730 to Terry et al., which is incorporated herein by reference, describes a method for treating motility disorders by applying a signal to the vagus nerve of a patient, in inhibit neural impulses, and produce excitatory or inhibitory neurotransmitter release by the nerve, according to the specific nature of the motility disorder.
U.S. Pat. Nos. 5,188,104 and 5,263,480 to Wernicke et al., which are incorporated herein by reference, describe a method for treating compulsive eating disorders by applying a stimulating signal to the vagus nerve of the patient appropriate to alleviate the effect of the eating disorder. For example, in cases where the disorder is compulsive eating, the stimulating signal is described as being calibrated to produce a sensation of satiety in the patient. In cases where the disorder is compulsive refusal to eat (anorexia nervosa), the stimulating signal is described as being calibrated to produce a sensation of hunger or to suppress satiety in the patient.
U.S. Pat. No. 5,571,150 to Wernicke et al., which is incorporated herein by reference, describes a method for treating a comatose patient by stimulating a cranial nerve, preferably the vagus nerve, in order to modulate the activity of the nerve in an effort to rouse the patient from the coma.
U.S. Pat. Nos. 4,702,254, 4,867,164 and 5,025,807 to Zabara, which are incorporated herein by reference, generally describe methods for controlling or preventing epileptic seizures and other motor disorders by stimulating the vagus nerve.
U.S. Pat. No. 6,205,359 to Boveja, which is incorporated herein by reference, describes apparatus for treating various forms of epilepsy and involuntary movement disorders by electrical stimulation of the left vagus nerve.
U.S. Pat. No. 5,205,285 to Baker, which is incorporated herein by reference, describes a device designed to avoid undesirable voice modulation of patients undergoing vagal stimulation therapy, while maintaining a bias in certain circumstances toward ongoing delivery of the therapy. In essence, this device requires the addition of sensing means to detect the patient's attempts at speech, responsive to which the device halts or delays the vagal stimulation during the time that speech attempts continue to be detected.
U.S. Pat. No. 5,299,569 to Wernicke et al., which is incorporated herein by reference, describes a method for treating and controlling neuropsychiatric disorders, including schizophrenia, depression and borderline personality disorder, by selectively applying a predetermined electrical signal to the patient's vagus nerve, in order to alleviate the symptoms of the disorder being treated.
U.S. Pat. No. 5,335,657 to Terry et al., which is incorporated herein by reference, describes a method for treating and controlling sleep disorders by applying an electrical signal to the vagus nerve in order to modulate electrical activity of afferent fibers of the nerve.
U.S. Pat. No. 5,707,400 to Terry et al., which is incorporated herein by reference, describes a method for treating patients suffering from refractory hypertension, also by stimulating the vagus nerve.
As is seen from this list of patents, stimulation of the nervous system, particularly the vagus nerve, for therapeutic purposes has been the subject of a considerable amount of research and application to medical, psychiatric, and neurological disorders. However, other than the problem of speech impairment addressed by the above-cited U.S. Pat. No. 5,205,285 to Baker, the possible unwanted side effects, both proven and potential, of selective stimulation of the vagus nerve, have not been given extensive consideration.
U.S. Pat. No. 5,282,468 to Klepinski, which is incorporated herein by reference, describes an implantable neural electrode.
U.S. Pat. No. 4,628,942 to Sweeney et al., which is incorporated herein by reference, describes an asymmetric, shielded, two-electrode cuff for stimulating a nerve.
U.S. Pat. No. 4,535,785 to van den Honert et al., describes implantable electronic apparatus.
U.S. Pat. No. 4,602,624 to Naples et al., which is incorporated herein by reference, describes an implantable electrode cuff for applying signals to nerves.
U.S. Pat. No. 5,199,430 to Fang et al., which is incorporated herein by reference, describes implantable electronic apparatus for assisting the urinary sphincter to relax.
U.S. Pat. No. 5,215,086 to Terry et al., which is incorporated herein by reference, describes a method for applying electrical stimulation to treat migraine headaches.
U.S. Pat. No. 5,755,750 to Petruska et al., which is incorporated herein by reference, describes a method for selectively inhibiting activity in nerve fibers.
U.S. Pat. No. 4,649,936 to Ungar et al., and U.S. Pat. No. 4,608,985 to Chrish et al., which are incorporated herein by reference, describe apparatus and methods for selectively blocking action potentials passing along a nerve trunk. PCT Patent Publication WO 01/10375A2 to Felsen et al., which is incorporated herein by reference, describes a method for inhibiting action potential generation in nervous tissue.
The following articles may be of interest, and are incorporated herein by reference:
“Generation of unidirectionally propagating action potentials using a monopolar electrode cuff,” Annals of Biomedical Engineering, vol. 14, pp. 437-450, 1986 by Ira J. Ungar et al.
“An asymmetric two electrode cuff for generation of unidirectionally propagated action potentials,” IEEE Transactions on Biomedical Engineering, vol. BME-33, No. 6, June 1986 by James D. Sweeney et al.
“A spiral nerve cuff electrode for peripheral nerve stimulation,” by Gregory G. Naples et al., IEEE Transactions on Biomedical Engineering, vol. 35, No. 11, November 1988.
“A nerve cuff technique for selective excitation of peripheral nerve trunk regions,” by James D. Sweeney et al., IEEE Transactions on Biomedical Engineering, vol. 37, No. 7, July 1990.
“Generation of unidirectionally propagated action potentials in a peripheral nerve by brief stimuli,” Science, vol. 206, pp. 1311-1312, December 1979.
“Generation of unidirectionally propagated action potentials in a peripheral nerve by brief stimuli,” van den Honert et al., 206 Science 1311-1312, (Dec. 14, 1979).
“A technique for collision block of peripheral nerve: Frequency dependence,” van den Honert, C., Mortimer, J. T.: MP-12, IEEE Trans. Biomed. Eng. 28:379-382, 1981.
“A technique for collision block of peripheral nerve: Single stimulus analysis,” van den Honert, C., Mortimer, J. T.: MP-11, IEEE Trans. Biomed. Eng. 28:373-378, 1981.
“A Nerve Cuff Design for the Selective Activation and Blocking of Myelinated Nerve Fibers,” D.M. Fitzpatrick et al., Ann. Conf. of the IEEE Eng. in Medicine and Biology Soc., Vol. 13, No. 2, pp. 906, 1991. The authors describe the use of a tripolar cuff electrode for generating unidirectional action potentials in nerve fibers according to their size, and conclude, “The results show that a tripolar cuff electrode can generate unidirectional action potentials in the small nerve fibres whilst blocking the large fibres. Changing the ratio of the anodal currents results in the gradual recruitment of the large fibres” (p. 907).
“Acute Animal Studies on the Use of Anodal Block to Reduce Urethral Resistance in Sacral Root Stimulation,” N.J.M. Rijkhof et al., IEEE Transactions on Rehabilitation Engineering, Vol. 2, No. 2, pp. 92, 1994. The authors describe experiments in which, using a tripolar electrode configuration and monophasic rectangular current pulses in acute canine experiments, a reduction of intraurethral pressure response, as compared to stimulation without blocking, of more than 80% was achieved. The authors write, “Our research is focused on selective activation of small nerve fibers in sacral roots by a combination of cathodal excitation of all fibers and a selective anodal block [1], [6]-[8] of the large fibers. . . . Since large diameter fibers need less current for their blocking than small ones [1], selective activation of small fibers is possible by blocking, distal to the excitation site (cathode), the propagation of the induced action potentials in the large fibers” (p. 92).
“Orderly Recruitment of Motoneurons in an Acute Rabbit Model,” N.J.M. Rijkhoff et al., Ann. Conf. of the IEEE Eng., Medicine and Biology Soc., Vol. 20, No. 5, pp. 2564, 1998. The authors describe the use of selective anodal blocking in an acute animal model to investigate the advantages of orderly recruitment. The authors write, “At least 3 different methods are known that allow for selective small fiber activation, selective anodal blocking, high frequency stimulation and slowly rising pulses [2]. A project has been started to compare these 3 different methods with respect to performance, stability, required electrical charge per pulse. This abstract reports on the results obtained with only one of these methods, the selective anodal block [3]” (p. 2564).
“Orderly Stimulation of Skeletal Muscle Motor Units with Tripolar Nerve Cuff Electrode,” R. Bratta et al., IEEE Transactions on Biomedical Engineering, Vol. 36, No. 8, pp. 836, 1989. The authors describe an electrical nerve stimulation technique, using a single tripolar electrode, that is capable of recruiting motor units according to their size, while allowing simultaneous but independent control of firing rate in the active units.
U.S. Pat. No. 5,423,872 to Cigaina, which is incorporated herein by reference, describes a method for pacing the stomach in order to alter its natural rhythm. The principle espoused in Cigaina is that by altering the rhythm, one can either delay or speed up gastric emptying. Cigaina indicates that many different disorders, including gastroesophageal reflux disorder (GERD), can be treated using the rhythm altering method.
U.S. Pat. No. 5,716,385 to Mittal et al., which is incorporated herein by reference, describes a system to treat GERD by stimulating the skeletal muscle tissue of the crural diaphragm whenever myoelectric measurements made on the diaphragm are indicative of relaxation thereof. Stimulation of the diaphragm is intended to indirectly cause contraction of the lower esophageal sphincter (LES), and thereby inhibit a reflux event which is assumed to accompany relaxation of the diaphragm.
U.S. Pat. No. 6,097,984 to Douglas, which is incorporated herein by reference, discloses a system to treat GERD by continually simulating the LES of a patient in order to maintain it in a closed state, thereby preventing reflux. Stimulation is removed only when swallowing is detected, to allow food pass into the stomach.
U.S. Pat. Nos. 6,104,955, 6,091,992, and 5,836,994 to Bourgeois, U.S. Pat. No. 6,026,326 to Bardy, U.S. Pat. No. 6,083,249 to Familoni, U.S. Pat. No. 5,690,691 to Chen, U.S. Pat. No. 5,292,344 to Douglas, and U.S. Pat. No. 3,411,507 to Wingrove, which are incorporated herein by reference, describe methods and apparatus for electrical simulation of the GI tract to treat various physiological disorders.